1. Field of the Invention
The present invention relates to a projector-type vehicle headlamp.
2. Description of the Related Art
A projector-type headlamp that effectively uses a part of light from the light source, which normally becomes useless, has been disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-324413 (see FIGS. 12 and 13). This headlamp includes a discharge bulb (22), a reflector (24) having a reflection surface (24a), a rotatably supported shade (72), a shade drive (34), a projection lens (28), a first additional reflector (36) having a reflection surface (36a), a second additional reflector (74) rotatably supported and having a reflection surface (74a), and a second additional reflector drive.
The shade (72) is positioned at a shading position, and the second additional reflector (74) is positioned downward. At this time, the light from the discharge bulb (22) is reflected by the reflection surface (24a) of the reflector (24), and a part of the reflected light is cut off by the shade (72), and the remaining reflected light passes through the projection lens (28) and is irradiated outward in a low-beam light distribution pattern (P(L)). On the other hand, a part of light from the discharge bulb (22), which normally becomes useless, is reflected by the reflection surface (36a) of the first additional reflector (36), and the reflected light is diffuse-reflected in the horizontal direction by the reflection surface (74a) of the second additional reflector (74), to form a downward and oblong additional light distribution pattern (P(A)). The downward and oblong additional light distribution pattern (P(A)) is superposed on the low-beam light distribution pattern (P(L)).
Furthermore, the shade (72) is positioned at a light transmitting position, and the second additional reflector (74) is positioned upward. At this time, the light from the discharge bulb (22),is reflected by the reflection surface (24a) of the reflector (24), and the reflected light passes through the projection lens (28) and is irradiated outward in a high-beam light distribution pattern (P(H)). On the other hand, the part of light from the discharge bulb (22), which normally becomes useless, is reflected by the reflection surface (36a) of the first additional reflector (36), and the reflected light is diffuse-reflected in the horizontal direction by the reflection surface (74a) of the second additional reflector (74), to form an upward and oblong additional light distribution pattern (P(A)). The upward and oblong additional light distribution pattern (P(A)) is superposed on the high-beam light distribution pattern (P(H)).
Thus, the headlamp effectively uses the light from the discharge bulb (22), which normally becomes useless. In other words, the headlamp can obtain a light distribution pattern in which the downward and oblong additional light distribution pattern (P(A)), which effectively uses the useless light, is superposed on the low-beam light distribution pattern (P(L)), and a light distribution pattern in which the upward and oblong additional light distribution pattern (P(A)), which effectively uses the useless light, is superposed on the high-beam light distribution pattern (P(H)).
However, the conventional headlamp simply uses the partial light from the discharge bulb (22), which normally becomes useless, as the oblong additional light distribution pattern (P(A)). Therefore, in the conventional headlamp, the position of the oblong additional light distribution pattern (P(A)) obtained by effectively using the useless light is changed up and down. However, there is a problem such that the shape and action (diffusing action and condensing action) of the oblong additional light distribution pattern (P(A)) itself does not change.